Tip-Half Square Triangles

HST Try these methods for constructing Half Square Triangles.

1. Rule for Measuring & Cutting: If you know the finished size for your HST Block, take that measurement and add 1″.  That is the easiest on your eyes.  The real rule says to add 7/8″ and you can do that, but an inch is so much easier to measure!  For example: 3″ HST: cut 2 squares of contrasting fabric 4″ in size. Mark the diagonal on one fabric. Stitch 1/4″ from each side of the marked line.  Cut the unit on the marked line (between your two lines of stitching).  Press open your 2 HSTs and trim to size.

2. HST Units: each unit makes 4 Half Square Triangles

The key to this method is remembering that when you refer to the chart for cutting dimensions, it starts with squares based on the FINISHED size of the square in your block or quilt.

Finished Size of HST:  ——- Cut 2 Fabric Squares:

1″ ————————————- 2 3/4″
1 1/4″——————————— 3″
1 1/2″——————————— 3 3/8″
2″ ————————————- 4 1/8″
2 1/2″ ——————————– 4 7/8″
3″ ————————————- 5 1/2″
3 1/2″ ——————————– 6 1/4″
4″ ————————————- 7″
4 1/2″ ——————————– 7 5/8″
5″ ————————————- 8 3/8″
6″ ————————————- 9 3/4″

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Sewing Directions:

  • Cut your squares to whatever size you need.
  • Place right sides together & sew 1/4″ seam all around the squares
  • Cut the sewn squares twice, diagonally, from corner to corner.
  • Trim your “dog ears” and you will have 4 nearly perfect Half Square Triangles
  • Beware: this method does leave you with open bias edges.

Other Methods:

  • Thangles
  • Templates